CVE-2021-41591 in Eclair
Summary
by MITRE • 10/04/2021
ACINQ Eclair before 0.6.3 allows loss of funds because of dust HTLC exposure.
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Analysis
by VulDB Data Team • 10/09/2021
The vulnerability CVE-2021-41591 affects ACINQ Eclair versions prior to 0.6.3 and represents a critical financial risk in lightning network implementations. This flaw specifically relates to how the software handles dust HTLCs or Hashed Time-Locked Contracts, which are fundamental components of the lightning network's payment routing mechanism. The issue manifests as a potential loss of funds due to improper handling of these small-value transactions that exist in the network's state machine.
The technical root cause stems from the software's failure to properly account for dust HTLCs during channel state updates and commitment transaction processing. In lightning network operations, HTLCs represent pending payments that must be resolved either through successful payment completion or timeout mechanisms. When these HTLCs fall below the minimum transaction value threshold defined by the network protocol, they become dust HTLCs and should be handled according to specific rules to prevent financial loss.
The operational impact of this vulnerability is severe as it allows malicious actors or system failures to exploit the improper dust HTLC handling to cause fund loss. When a channel encounters a dust HTLC that is not properly managed, the commitment transaction state can become inconsistent, leading to scenarios where funds can be permanently lost or misallocated. This risk is particularly dangerous in multi-hop payment scenarios where the vulnerability could be exploited across multiple nodes in a payment route.
The vulnerability aligns with CWE-400 vulnerability class related to unspecified vulnerability in resource management and demonstrates characteristics consistent with ATT&CK technique T1499.004 related to data destruction. The flaw essentially creates a condition where the software fails to properly validate and handle edge cases in its state machine, leading to potential financial loss. This type of vulnerability is particularly concerning in cryptocurrency implementations where financial loss can occur through improper state transitions.
Mitigation strategies include upgrading to ACINQ Eclair version 0.6.3 or later, which contains the necessary fixes for proper dust HTLC handling. Network operators should also implement additional monitoring for channel states and HTLC processing to detect anomalous behavior. The fix typically involves implementing proper validation of HTLC values during commitment transaction creation and ensuring that dust HTLCs are handled according to established lightning network protocol specifications. Organizations should also conduct thorough testing of their lightning network implementations to verify proper handling of edge cases and ensure that no similar vulnerabilities exist in their deployment configurations.